1. Field of the Invention
The present invention relates to an image forming apparatus having document conveying means for conveying a document to a predetermined read position. More particularly, the present invention relates to a silent image forming apparatus in which document conveying means can operate with reduced operating noise during a document reading process in a standby state.
2. Description of Related Art
Some conventional image forming apparatuses, e.g., copying machines have an automatic document feeder provided as a means for conveying a document to be read to a predetermined read position. In such image forming apparatuses, a document to be copied is first placed on a document tray of the document feeder and is then conveyed automatically to the position on a platen glass, followed by reading of the document image with reading means.
In recent years, copying machines such as digital copying machines and digital combination machines having functions corresponding to the functions of a copying machine, a facsimile machine and a printer have come on the scene. Such copying machines include a type using a procedure for improving the productivity as described below. During standby before the temperature of a fixing device of the copying machine is increased to a predetermined (fixing) temperature, a document is read before a copying operation and document information obtained by reading the document is stored in a memory to enable the copying operation to be started immediately after the standby state.
On the other hand, automatic document feeders provided in such copying machines include a type designed so as to achieve a space saving effect as well as an improvement in productivity, for example, in such a manner that, while information written on a document separated and taken up from a top of a batch of documents is being read by reading means, a preceding document can be independently discharged in a reversed state.
Further, copying machines having such an automatic document feeder include a machine designed so as to achieve an improvement in productivity and matching with an arrangement relating to discharge of a top page from a printing unit in such a manner that copy output sheets are discharged by reversing discharge (discharge of sheets with the back surface up) in order in correspondence with the order of documents from the first page.
With respect to the above-described conventional copying machines (image forming apparatus), it has been pointed out that, in a case where a copying machine arranged as described above is placed in a quiet office, a user may have a feeling of discomfort due to operating noise caused during standby by the above-described operation for reading a document before a start of a copying operation.
In a case where an arrangement enabling independent reversing discharge of a preceding document is adopted for the purpose of achieving a space saving effect and improving the productivity of a copying machine, the document reversing discharge operation and the discharge operation of a copying machine main unit are performed substantially in synchronization with each other. In this case, therefore, the operating noise caused by the operation of the entire system formed of the copying machine main unit and the automatic document feeder in combination is increased.
The conveying speed for the reversing discharge operation selected to ensure increased productivity is about twice as high as feeding speed and the conveying speed during times other than when the reversing discharge operation is performed. Therefore the operating noise problem with the conveying speed for the reversing discharge operation is particularly serious and the resulting influence on users in a quiet office environment is considerable and there has been a demand for a solution to the problem.
In view of the above-described circumstances, an object of the present invention is to provide a silent image forming apparatus capable of operating with reduced operating noise.
To achieve the above-described object, according to the present invention, there is provided an image forming apparatus which forms an image on a sheet, including document conveying means for conveying a document to a predetermined read position, reading means for reading an image from the document conveyed to the read position, an image forming part which forms a toner image on and image bearing body on the basis of document image information read by the reading means, the apparatus being characterized in that the apparatus is controlled so that, in a standby state before the image forming part becomes able to perform image forming, documents are successively conveyed to a predetermined read position on a platen glass by the document conveying means and images are read from all the documents, and so that, at the time of document image reading in the standby state, operating noise from the document conveying means is reduced.
Also, according to the present invention, the image forming apparatus is characterized by including detecting means for detecting the standby state, and controlling means for performing in the standby state a control process in which drive of the document conveying means performed by drive means is controlled on the basis of a detection signal from the detecting means so that the operating noise is reduced.
Also, according to the present invention, in the image forming apparatus, it is characterized in that at the time of document image reading in the standby state, the controlling means controls drive of the document conveying means performed by drive means so that the speed at which the document is conveyed is reduced.
Also, according to the present invention, in the image forming apparatus, it is characterized in that at the time of document image reading in the standby state, the controlling means controls drive of the document conveying means performed by drive means so that the document read interval is increased.
Also, according to the present invention, in the image forming apparatus, it is characterized in that the document conveying means includes a reversing discharge part which reverses the document after conveying to the read position and after reading, and discharges the reversed document, and that at the time of document image reading in the standby state, the controlling means controls drive of the document conveying means performed by drive means so that document conveying speed when the reversing discharge is performed is reduced.
Also, according to the present invention, in the image forming apparatus, it is characterized in that the detecting means detects the standby state at least from a fixing temperature of fixing means for fixing, by heating and pressing, a toner image formed on an image bearing body and thereafter transferred onto the sheet in the fixing temperature of the fixing means and a surface potential on the image bearing body.
Also, according to the present invention, in the image forming apparatus, it is characterized in that the controlling means selectively performs a control process in which after the machine has entered a state where image forming can be performed, and after reading of all document images has been completed, the image forming operation by the image forming part is initiated.
Also, according to the present invention, the image forming apparatus is controlled so that, in a standby state before an image forming part becomes able to perform image forming, documents are successively conveyed to the predetermined read position by the document conveying means and images are read from all the documents, and so that, at the time of document image reading in the standby state, operating noise from the document conveying means is reduced.
Also, according to the present invention, as described above, the image forming apparatus is controlled so that, in a standby state before an image forming part becomes able to perform image forming, documents are successively conveyed to the predetermined read position by the document conveying means and images are read from all the documents, and so that, at the time of document image reading in the standby state, operating noise from the document conveying means is reduced. Thus, it is possible to provide a silent image forming apparatus which can operate with a level of operating noise low enough to ensure that a user does not have a feeling of discomfort.